This study examines the Personal Practical Theories (PPTs) of preservice elementary school teachers in mathematics education and explores their sources, categorizing them into four main themes: teacher identity, instructional practices, assessment strategies, and learning environment. Analysis reveals that the most influential sources shaping PPTs are the preservice teachers' own experiences as students, highlighting the significant impact of past educational encounters on their personal theories. Additionally, theoretical courses at the faculty and insights gained from former teachers play crucial roles in shaping these theories. Understanding these influences can inform the development of tailored teacher training programs, better preparing preservice teachers for effective classroom instruction.